Kuru Was No Laughing Matter

By Stephen Luntz

Michael Alpers’ work in Papua New Guinea helped to explain one of the strangest known diseases, and opened the way to understanding several related infections.

When Prof Michael Alpers went to the Fore territory of Papua New Guinea in 1961, the people were dying of an apparently inexplicable disease. Known as kuru, the neurological condition’s name comes from a local word meaning “to shake”. Sufferers became weak, started to shake and had uncontrollable bursts of laughter. It was always fatal.

Kuru’s cause was particularly obscure. Was it a genetic or an infectious disease? If infectious, what was the transmissive agent?

No sign of a bacterium or virus existed. The disease was clearly in decline, but this only added to the mystery.

If kuru was infectious it required an incubation period far longer than any then-known disease, indeed longer than was generally considered possible. A hint of the cause lay in the Fore people’s practice of eating the dead as a sign of respect. Adult men ate the choice cuts, while women and young children, the primary victims of kuru, consumed the organs.

Alpers had graduated in medicine from Adelaide University earlier that year. The department had done some work in New Guinea, then an Australian colony, and Alpers had developed an interest in the area. He’s unsure why, but says he “always wanted to be a medical researcher. My father was a country doctor, so the medical side isn’t too hard to explain, but I don’t know where the interest in research came from. I studied physics and maths for a while, but switched back to medicine because it was more connected to people.”

In New Guinea, Alpers teamed up with Daniel Gajdusek, who was later awarded the Nobel Prize for demonstrating the infectious nature of kuru.

The lucky break, however, came on the other side of the world. A vet named William Hadlow saw an exhibition on kuru and immediately noticed the similarity to the sheep disease scrapie, which was already known to be infectious with an extraordinarily long incubation.

Alpers and Gajdusek set out to explore this possibility. The crucial experiment was to inject material from the brain of a kuru victim into primates. Several experiments failed because laboratories didn’t keep the test animals long enough, but the scrapie example encouraged the preservation of a chimpanzee until she showed symptoms.

The outlawing of cannibalism in the 1950s had largely ended kuru’s transmission, but the long incubation time meant that deaths continued to occur into this century.

Nevertheless Alpers’ discovery may well have saved numerous lives. The Fore people had initially blamed kuru on sorcery. “When someone got sick, a lot of effort would go into finding the sorcerer,” Alpers says. This person would often be killed in retribution. Although many of the older Fore did not accept Alpers’ explanation, enough doubt was created that revenge killings sank.

The capacity of kuru and scrapie to survive decontamination procedures were eventually explained by both being caused by prions – proteins that by folding into an unusual shape can damage nerve cells. The process by which a prion causes other proteins to fold incorrectly remains a mystery.

It is suspected that the first case of kuru came about through a random mutation, probably around 1900. This generated a case of Creutzfeld-Jakob Disease (CJD), a neurological condition that spontaneously appears in roughly one person in a million. The Fore’s mortuary practices turned an individual’s tragedy into an epidemic.

For many years Alpers’ work appeared something of a medical curiosity, however it took on unexpected significance when a similar disease nearly brought the British economy to its knees through the widespread development of mad cow disease. This is also caused by a prion, and is transmitted when calves are fed the brains of other cows.

Turning herbivores to cannibalism might appear as stupid as it turned out to be, but calves grow faster on the high protein diet. As Alpers puts it: “The industry was making a lot of money. Why stop simply because of evidence that might not develop?”

Once problems emerged, the feeding of cows to other cows was banned. However, cows could still be fed to pigs and, as Alpers says: “If you’re on a mixed farm it was easy for contamination to occur”.

Mad cow disease led to awful deaths for many bovines and the culling of more than four million animals. So far, 166 people have caught a form of CJD from eating infected cows, a disaster that could have been prevented had Alpers’ work been heeded.

In 1977 Alpers became Director of the Papua New Guinea Institute of Medical Research. In 23 years he expanded the number of scientists at the Institute from ten to 250, and his work on pneumonia, malaria and other diseases made a major contribution to raising life expectancy in PNG.